After ten weeks of development Linus Torvalds has announced the release of Linux kernel 3.9. The latest version of the kernel now has a device mapper target which allows a user to setup an SSD as a cache for hard disks to boost disk performance under load. There's also kernel support for multiple processes waiting for requests on the same port, a feature which will allow it to distribute server work better across multiple CPU cores. KVM virtualisation is now available on ARM processors and RAID 5 and 6 support has been added to Btrfs's existing RAID 0 and 1 handling. Linux 3.9 also has a number of new and improved drivers which means the kernel now supports the graphics cores in AMD's next generation of APUs and also works with the high-speed 802.11ac Wi-Fi chips which will likely appear in Intel's next mobile platform. Read more about new features in What's new in Linux 3.9.

Now which one is the most usable ? Which is the most portable ? FPU support was added to Minix3 through a Google Summer of code, have no extension support (MMX, SSE, ...) and do not run on ARM.

Linux, on the other hand...

You're comparing something designed for students to learn from to a commercial OS backed by large companies (RedHat, Novell, Intel, IBM, Oracle, Google, etc)? Are you the sort of person that does a victory lap after they've stepped on a small bug?